Determine if variable is defined in Python [duplicate]

python variables defined

try:    thevariableexcept NameError:    print("well, it WASN'T defined after all!")else:    print("sure, it was defined.")

python variables defined

'a' in vars() or 'a' in globals()

if you want to be pedantic, you can check the builtins too
'a' in vars(__builtins__)

python variables defined

I think it's better to avoid the situation. It's cleaner and clearer to write:

a = Noneif condition:    a = 42

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